CSE 100

<math.h>

Input: cin

type casting

Math Library Functions

math.h

sqrt(n)fabs(n)cos(n)log10(n)log(n)pow(b, n)etc.

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Math Library Functions

name of the function

what it does

data type of argument

data type of returned value

Math Library Functions

Syntax: function_name (argument);function_name (argument);

Ex. sqrt(49) pow(2.1, 3)

abs(-34.5) cos(30)

abs(34.5)

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Math Library Functions

nested functions

sqrt( pow ( fabs (-4), 3) ) =

sqrt( pow ( 4.0 , 3) ) =

sqrt( 64.0 ) = 8.0

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Type Casting

The explicit conversion of a value from one data type to another.

Syntax: data_type (expression)data_type (expression)

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int (5.34 * 1.68)

int (8.9712)This returns a value of 8.

Type Casting

someInt = someDouble - 8.2;

someInt = int(someDouble - 8.2);

These are identical statements.These are identical statements.

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Type Coercion

The implicit (automatic) conversion of a value from one data type to another.

someDouble = 42; is stored as 42.0

someInt = 11.9; is stored as 11

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Math Function Example

#include <math.h> // needed for the exp functionint year;int year;long int population;long int population;

year = 1995;year = 1995;

population = 5.5 * population = 5.5 * exp(exp(0.02*(year-1990)0.02*(year-1990)));;cout << "The estimated population for " << yearcout << "The estimated population for " << year

<< " is "<<population << "."; << " is "<<population << ".";

year = 2012;year = 2012;cout << "The estimated population for " << yearcout << "The estimated population for " << year

<< " is "<< population <<"."; << " is "<< population <<".";

Math Function Example

5.5 ee .02(year-1900)

5.5 * 5.5 * expexp((0.02*(year-1990)0.02*(year-1990)))

Math Function Example

Output:

The estimated population for 1995 is 6.

The estimated population for 2012 is 8.

cin

cin >> my_num;

The keyboard entry is stored into a local

variable called my_num.

Read as: “get from my_num”.

cin

Syntax: cin >> var1;cin >> var1;

Examples:

cin >> last_name;

cin >> ch;

cin >> my_id#;

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cin(concatenation)

Syntax: cin >> var1 >> var2 >> ...cin >> var1 >> var2 >> ...

cin >> first >> last >> my_num;

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cin >> qz1 >> qz2 >> qz3 >> qz4;

cin & cout

standard device standard device (keyboard) (screen)

main(){cout <<cin >>}

cin & cout

cout cin

<< >>

insertion extraction

“put to” “get from”

whitespace characters ignored

cin Example 1

int num1, num2, num3;double average;

cout << "Enter three integer numbers: ";cin >> num1 >> num2 >> num3;average = (num1 + num2 + num3) / 3.0;cout << "The average is " << average;cout << '\n';

cin Example 1

Output:

3 5 5

The average is 4.33333

cin Example 2

double radius, circumference;

double pi = 3.1416;

cout << "Enter the radius of a circle: ";

cin >> radius;

circumference = 2 * pi * radius;

cout << "The circumference of a circle of radius "

<< radius << " is " << circumference <<‘\n’;

cin Example 2

Output:

Enter the radius of a circle: 14

The circum ... circle of radius 14 is 87.9648

cin Example 3

double celsius, faren;

cout <<"Enter the temperature in degrees Fahrenheit: ";cin >> faren;

celsius = 5.0/9.0 * (faren - 32.0);

cout << faren <<" degrees Fahrenheit equals "<< celsius << " degrees celsius.\n";

cin Example 3

Output:

Enter the temperature in degrees Farenheit: 8282 degrees Farenheit equals 27.7777 degrees celsius.

const Qualifier

Syntax: const DataType Name = Literal Value;const DataType Name = Literal Value;

Examples

const double PI = 3.1416;

const double OT_RATE = 1.5;

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const Qualifier

double radius, area;

const double PI = 3.1416

cout << “Enter the radius: “;

cin >> radius;

cout << “The area is your circle is “

<< PI * radius * radius;

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Common Programming Errors

not initializing variables before useforgetting >>>> to separate variables in cin

applying ++++ or ---- to an expression

(x-y)++

Why isn’t phonetic spelled as it sounds?

Why do they put Braille dots on the keypad of a drive-up ATM?

How many Microsoft technicians does it How many Microsoft technicians does it take to change a light bulb?take to change a light bulb? Three: two holding the ladder and one

to screw the bulb into a faucet.

“Lack of brains hinders research” The Columbus Dispatch, 16 April 1996